Tomasz, On Thu, Jun 5, 2014 at 12:31 PM, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote: > One more question that just came to my mind: Why it is just the > aclk66_peri and not its children related to UARTs? Can you re-read out the original patch description and see if it answers that? Basically: the UART was left on by the bootloader and that's a requirement of earlyprintk but the common clock framework is messing with aclk66_peric which is what's killing us. > Exynos5420 clock driver still needs a little clean-up, so I'm okay with > any fix for now and changing this later if needed, but is this gate > clock for ACLK66_PERIC even needed? It seems to be marked with > CLK_IGNORE_UNUSED which suggests that it is not needed in this driver at > all, along with other similar clocks. AFAIK for power management > purposes our fine-grained approach is fine and we shouldn't need to use > the big gates. Right, another option is to remove this gate from the clock tree (and reparent all children on the gate's parent) and that would also fix us. The main advantages of the "big gate" as I see it: 1. There's a reasonable chance that our clock tree description is not complete. Patches to add previously undocumented clocks seems to be a relatively common occurrence. If one of those undocumented clocks happens to be a child of aclk66_peric then we'll no longer be gating it. 2. There might be a small amount of power saved by gating the clock higher in the tree. 3. Having a more complete description of the clock tree is nice in case someone outside the kernel does something. If a stray pointer (or a nonstandard bootloader) gates the clock then our tree won't show problems, but the clock will still be gated. Of course as soon as the first child of aclk66_peric is activated then points #1 and #2 are invalid. ...and #3 is a bit bogus because there are A LOT of gates that we already don't model. Also: the CLK_IGNORE_UNUSED is a bit bogus here. That's not really a useful flag in the case that you've got children that are enabled and disabled. Once your first child is enabled and disabled you'll be disabled! --- Hmmm, I think I've convinced myself that your suggestion of just removing this gate from the table is the right thing to do. Patch will be coming up soon. -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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